The disclosure of Japanese Patent Application Nos. HEI 11-98863 filed on Apr. 6, 1999 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to an internal combustion engine control apparatus and, more particularly, to a control apparatus for controlling the revolution of an internal combustion engine during a post-startup of the internal combustion engine (hereinafter, xe2x80x9cpost-startupxe2x80x9d means a period that immediately follows the startup of the engine and, more specifically, extends from the initial ignition of engine fuel until the internal combustion engine enters an idle steady state).
2. Description of the Related Art
For reducing atmospheric pollution, various automotive technologies have been, and are being, developed to reduce emissions. In this respect, improvements in emission control during a period after startup of an internal combustion engine are becoming increasingly important, and it is now demanded that during a post-startup of an internal combustion engine, the internal combustion engine be controlled with good precision and without variations. In particular, it is strongly demanded that the engine revolution during the post-startup be controlled with good precision in an intended manner, because the engine revolution during post-startup has a great and direct effect on the emissions quality.
A related internal combustion engine technology that controls the throttle opening extent so that the engine revolution reaches a target value corresponding to the engine temperature is disclosed in, for example, Japanese Patent Application Laid-Open No. SHO 62-3139.
However, the combustion in an internal combustion engine is affected not only by the engine temperature but also by various ambient conditions (e.g., ambient pressure, temperature, humidity, etc.), differences among individual engines due to variations caused during manufacture, aging of the engine, the properties of a fuel used, and the like. The effects of such factors are particularly great during the startup and during the post-startup. For example, the properties of a fuel vary depending on crude oil sources, refinery companies (and facilities of a single company), seasons of refinery (a heavy fuel containing reduced volatile components for a summer season, and a light fuel containing increased volatile components for a winter season), and the like.
FIG. 9 is a graph indicating different patterns of changes in the engine revolution during the post-startup caused by different fuel properties, where a solid line indicates a light fuel containing increased volatile components, and a broken line indicates a heavy fuel containing reduced volatile components. As indicated in FIG. 9, the engine revolution during the post-startup is considerably affected merely by the fuel properties. Various other effects are also caused by other factors as mentioned above. Therefore, it requires great amounts of manpower to find optimal set values (points of compromise) in the control of an internal combustion engine based on considerations of various effects as mentioned above. Furthermore, even if optimal values are set after a great amount of study, exposure of the internal combustion engine to a condition outside the design condition range will likely result in deterioration of combustion and degradation of emission quality.
Accordingly, it is an object of the invention to provide a control apparatus and a control method capable of controlling the revolution of an internal combustion engine during post-startup with good precision so that the post-startup revolution follows a target change pattern, without being affected by differences among individual internal combustion engines, environmental conditions, properties of a fuel used, etc.
To achieve the aforementioned and other objects, a control apparatus of an internal combustion engine in accordance with one aspect of the invention includes a post-startup revolution change index learner that stores and updates an index of a characteristic of a revolution of the internal combustion engine during a post-startup period, and a controller constructed so as to control a control quantity for controlling the revolution of the internal combustion engine during the post-startup period so that the revolution during a next post-startup period substantially follows a target characteristic, based on the index learned by the post-startup revolution change index learner. In the thus-constructed control apparatus, a post-startup revolution change index is learned, and the post-startup revolution of the internal combustion engine is controlled so that the revolution during the next post-startup period substantially follows a target characteristic, based on the learned index. As a result, the post-startup engine resolution speed does not vary, and the emission quality becomes stable, thereby contributing to the environment.
The controller may be constructed so as to control at least one of the amount of air taken into the internal combustion engine, the ignition timing, and the amount of fuel injected in the internal combustion engine. The thus-constructed controller is able to perform a control such that the next post-startup engine revolution exhibits a target characteristic by controlling at least one of the amount of intake air, the ignition timing and the amount of fuel injected, based on the index learned by the post-startup revolution change index learning device.
In a control method of an internal combustion engine in accordance with another aspect of the invention, an index of a characteristic of a revolution of the internal combustion engine during a post-startup period is stored and updated, and a control quantity for controlling the revolution of the internal combustion engine during the post-startup period is controlled so that the revolution during the next post-startup period substantially follows a target characteristic, based on the learned index. In this internal combustion engine control method, a post-startup revolution change index is learned, and the post-startup revolution of the internal combustion engine is controlled so that the revolution during the next post-startup period substantially follows a target characteristic, based on the learned index.